Density: LYTAG® is a lightweight aggregate with a bulk density at point of supply of approximately 810 kg/m3. (ie volume for volume Lytag ® Concrete Aggregate is approximately half the weight of "normal" limestone or gravel aggregate).

Moisture Content: As supplied 4-8mm LYTAG ® is likely to contain a natural moisture content of approximately 15%.

Description & Application:
Lytag® is a sintered lightweight honeycomb aggregate that is resistant to frost and chemicals, and will not break down in water. It is also non-combustible and has excellent sound and thermal insulation properties.

This selected grading of Lytag® contains a minimum of "fines", and is offered for the onsite production of lightweight floor and roof screed basecoats.

Lytag® lightweight screed basecoat is required to be topped off with a standard cement/sand topping.

Principal Advantages of Lytag Lightweight Screed

Low Density - Approximately half the weight of a sand/cement screed, providing significant weight savings and ease of manual placement
Reduced Cost - Made with approximately half the cement of conventional sand screeds.
Quicker Drying Out - Free passage of air through the no fines structure ensures a quicker drying rate.
Low Shrinkage A Lytag® no fines basecoat exhibits low shrinkage ( 0.04%) therefore laying in bays is unnecessary.
Thermal Conductivity λ of Lytag® Lightweight Screed is between 3 to 4 times lower than conventional sand screed
Falls - Ideal material for constructing falls as there is no maximum depth to which it can be laid.

Design Considerations: Applicable to both Lytag® floor and roof screeds. For full details see Lytag® Technical Manual Section 7

Strength / Mix Design A 10:1 4-8mm Lytag:Cement will achieve a 6.0 N/mm2 compressive strength. When topped with the recommended 15mm of sand screed this can withstand the point loading associated with office equipment etc.

Maximum Recommended Thickness - Basecoat:
Unlike conventional concrete screeds there is no maximum thickness to which Lytag® No Fines Light Weight Screed Basecoat can be laid. However, at depths in excess of 100mm consideration may be given to utilising 8-14mm Lytag® for greater ease of mixing and placement.

Minimum Recommended Thickness Sand Screed Topping: 15mm

Laying: Lytag® no fines screed should be laid and tamped by hand - mechanical placement should not be used.
The finished basecoat should be covered with sheeting to prevent drying out

The cement topping should be laid once the basecoat has sufficiently hardened to support foot traffic . Self leveling screeds should not be used as these will flow into the voids of the no fines basecoat

Source:
LYTAG ® lightweight screed aggregate is manufactured in the UK from reclaimed power station fuel ash (PFA).
Lytag® is made by pelletising and sintering pulverised fuel ash in a rotary kiln at a very high temperature. As it is fired, moisture in the pellets expands to produce a honeycombed core while the outside surface of each granule fuses to a ceramic shell. The resulting granules are lightweight, porous, and have a high resistance to crushing.

Environmental Considerations:
Lytag® is manufactured from former coal fired power station ash, hence allowing for land formerly used for landfill to be reinstated.
As Lytag is approximately 50% the weight of “normal”aggregate, twice the volume can be carried, reducing vehicle movements both on and off highway.
For a given volume, bound Lytag® Concretes and screeds use less cement, therefore providing a significant energy saving.